Self-cleaning helical spring filter and methods

ABSTRACT

Methods for cleaning sand from a helical spring sand filter, methods for assembling a self-cleaning helical spring sand filter, and a self-cleaning helical spring sand filter for use at the petroliferous unconsolidated sand strata of an oil well are disclosed. The filter comprises a helical spring connected in tension at each end to an elongated perforated sleeve for spacing apart all convolutions by a predetermined distance for forming the filter. One or more washer shaped cleaning rings with square holes therein are mounted between adjacent convolutions at one end of the spring for being rotated by a square ended rod supported by a sucker rod in a well between all of the convolutions to the spring other end for scraping off all foreign material from between the convolutions. The spring sand filter can be cleaned for as many times as there are cleaning rings instead of making trips to the surface for unclogging.

BACKGROUND OF THE INVENTION

Over the surface of the earth there are many thousands of oil wells thatare drilled and completed in unconsolidated sand, i.e. crumblysandstone. In such wells, sand does not necessarily precipitate to thebottom of the well, but instead may remain in suspension and is pumpedup, if not free flowing, with the oil. As a result, most mechanicalparts as valves, bearings, pistons, cylinders, etc. wear out prematurelyunder such conditions. Accordingly, the sand must be filtered out fromthe oil, preferably in the well. Petroleum companies have spent largesums of money in trying to find a suitable solution to the sand problem,but heretofore there has been no satisfactory method or long lastingdevice for preventing the entry of sand into the tube string andeventually into the suction pipe of the pump, or other works.

U.S. Pat. No. 2,837,032 discloses an oil well foam and wire coil filter,but that filter is quite sophisticated and expensive to manufacture, andis not adjustable to be opened for backwashing a cleaning liquid, aswater, to clean the clogged filter. Another attempted solution was aspring filter as disclosed in U.S. Pat. No. 3,754,651, but because nospacers are apparent between the helical filter elements, the elementswould have to be held in slight tension to separate the helical filterelements during filtering. Thus that filter could not be used as an oilwell filter on which high compressive loads may be placed. Likewise noguide tube or mandrel can be utilized to strengthen the compressivecapabilities for converting the filter to one for use in wells. Also,the spring filter of U.S. Pat. No. 3,179,116 is capable of beingstrengthened to use in wells. Any compressive force on the triangularspring elements would cause them to collapse, and further the coineddepressions for separating the spring elements would cause the springelements to flex with a load thereon causing displacement of theadjacent coils and variation of the gauge therebetween.

Thus, new and better methods for filtering sand from an oil well, bettermethods for forming and assembling helical spring sand filters, andbetter self-cleaning helical spring sand filters are required formounting on the lower end of a tubing string extending down into a wellto the oil containing sand strata.

The disclosed inventions are improvements over those of Assignee's U.S.Pat. Nos. 3,901,320 (166-311) and 3,937,281 (166-233).

OBJECTS OF THE INVENTION

Accordingly, a primary object of this invention is to provide a methodfor cleaning a helical spring filter.

Another primary object of this invention is to provide a method forforming or assembling a self-cleaning helical spring filter.

Yet another primary object of this invention is to provide a new andbetter self-cleaning helical spring filter.

A further object of this invention is to provide a method for cleaning ahelical spring filter and a mechanism for carrying out the method thatis easy to operate, is of simple configuration, is economical to buildand assemble, and is of greater efficiency for the filtering of sand outof oil deep in an oil well.

Other objects and various advantages of the disclosed method forcleaning a helical spring filter, method for forming or assembling ahelical self-cleaning sand filter, and a self-cleaning helical sandfilter will be apparent from the following detailed description,together with the accompanying drawings, submitted for purposes ofillustration only and not intended to define the scope of the invention,reference being made for that purpose to the sujoined claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings diagrammatically illustrate by way of example, not by wayof limitation, one form of the invention wherein like reference numeralsdesignate corresponding parts in the several views in which:

FIG. 1 is a schematic diagrammatic view with parts in section of the newsand filter as mounted in a typical oil well;

FIG. 2 is a schematic diagrammatic longitudinal cross-section of theself-cleaning helical spring filter, prior to lowering of the elongatedrod for cleaning of the filter;

FIG. 3 is the helical spring filter of FIG. 2 preparatory to cleaning ofthe filter by engagement of the square ended rotatable rod with thecleaning ring; and

FIG. 4 is a section at 4--4 on FIG. 3.

The invention disclosed herein, the scope of which being defined in theappended claims is not limited in its application to the details ofconstruction and arrangements of parts shown and described, since theinvention is capable of other embodiments and of being practiced orcarried out in various other ways. Also, it is to be understood that thephraseology or terminology employed here is for the purpose ofdescription and not of limitation. Further, many modifications andvariations of the invention as hereinbefore set forth will occur tothose skilled in the art. Therefore all such modifications andvariations which are within the spirit and scope of the invention hereinare included and only such limitations should be imposed as areindicated in the appended claims.

DESCRIPTION OF THE INVENTION

This invention comprises a new method for cleaning a sand filter, a newmethod for forming or assembling a self-cleaning helical spring sandfilter, and an apparatus comprising a new self-cleaning helical springsand filter, particularly for use in an oil well.

METHOD FOR CLEANING A SAND FILTER

Briefly and basically, the new method for cleaning a helical spring sandfilter (16) comprises the basic step of,

(1) rotating a cleaning ring (26) between the adjacent springconvolutions from one end of the helical spring (19) sand filter to thefilter other end for scraping off all foreign material from between thespaced apart spring convolutions.

This method step may be expanded to include,

(1) rotating an elongated rod (29) with a polygon shaped end (30)extending through the helical spring filter, and

(2) rotating, consecutively, each of a plurality of cleaning rings withcorresponding polygon shaped holes therein between the adjacent springconvolutions from one end of the helical spring filter to the filterother end with the polygon shaped rod end protruding therein forscraping off all foreign material from between the spaced apart springconvolutions for as many times as there are polygon shaped cleaningrings.

THE PREFERRED EMBODIMENT FOR PRACTICING THE INVENTION

The above methods for cleaning a helical spring sand filter may beperformed by other mechanisms than that disclosed in the FIGURES. Themechanism disclosed herein may be operated by or made by other methodsthan those disclosed, as by hand. However, the preferred system forperforming the method is disclosed in FIG. 2.

ARTICLES FOR PERFORMING THE METHODS

Self-cleaning helical spring filters are disclosed in the drawings thatmay be made by other methods, as by hand.

FIG. 1 is a schematic diagrammatic view of a typical producing oil well10 having pumping equipment 11 comprising motor means 12 for actuatingwalking beam 13 with horse head 14 for operating pump 15 in the well. Acrude oil pump is utilized after free flow has ceased for raising theoil that has passed through the filter 16 from the petroliferousunconsolidated sand 17 up to the surface to exit from discharge pipe 18.Except for the filter 16, all of the above parts may be conventionalelements.

FIG. 2 illustrates a schematic enlarged sectional view of the preferredmodification of the new self-cleaning helical spring filter 16 forperforming the above described methods. This filter 16, FIG. 2,comprises a helical square spring 19, two short inner sleeves 20, 21,one large outer sleeve 22, a plurality of cleaning rings or washers 25,26, having square holes 27 and 28, respectively, and a long cleaningring rotating rod 29.

While various polygon shapes may be utilized for the wire or bar stockfor forming the spring 11, square bar stock is preferred in this case.After the helical spring is formed and cut to a precise length, each endis welded to a short inner sleeve 20 and 21, respectively, FIG. 2. Thelower end of the spring 11 is secured to the lower end of an elongated,perforated outer sleeve 22, as by a pin 23 connecting the short innersleeve 20 to the lower end of the elongated sleeve 22. While this outersleeve 22 may have holes, slots, or openings of various shapes thereinto permit the oil to flow through from the formation to the screen orfilter 16, the disclosed perforated outer sleeve comprises a wide metalband wound around and formed to the desired diameter, with a ring ateach end, if so desired, to maintain its fixed diameter. Then the otherspring end is twisted until the helical spring 19 slides freely in outersleeve 22 and expanded to provide the exact predetermined spacingbetween the convolutions for screening of the sand or other foreignmaterial before a hole is drilled in the outer sleeve upper end and apin 24 inserted.

A packer 31 is rigidly secured to the lower end of outer sleeve 22 inthe well 10 adjacent the strata of petroliferous unconsolidated sand 17,FIG. 1.

Next, one or more cleaning rings 25, 26, FIG. 2, are inserted in thelower end of the helical spring between two adjacent convolutions, ifnot threaded in the end prior to welding on of the lower short innersleeve 20.

When the conventional filter becomes clogged with sand or other foreignmaterial, it is raised to the top of the well, cleaned, and then loweredagain. Instead, in this filter, an elongated round bar 29, FIG. 2, witha square end or head 30 is lowered from a sucker rod above and insertedfirst into the square hole 28. Upon rotation of the elongated round bar29 and immediate lifting thereof, the speed of lift being controlled bythe rate of rotation, the cleaning ring 26 scrapes and cleans betweenall the spring convolutions to the other end or top of the helicalspring where it comes to a stop against the other inner sleeve 21. Whilethe head 30 of the round bar 29 is square, the rest of the bar is roundof reduced diameter so that rotation thereof does not affect thecleaning rings already stowed at the upper end of the helical spring.

During cleaning of the helical spring convolutions, the filtered fluidfollowing the cleaning ring 26 continues to rise with the cleaning ringas it rotates from the lower end to the upper end of the helical springscreen. There, the filtered liquid passes between the reduced roundportion 29 of the bar and the larger square opening 27 in the ring tocontinue on up to the surface.

When the filter has become clogged again with sand or other foreignmaterial, the square headed elongated bar is again lowered into the wellto protrude through the cleaning ring at the top of the helical springfilter to pass down to enter the next remaining cleaning ring. After thesquare head 30 FIG. 2 is positioned in the square hole of the nextcleaning ring, as ring 25, FIG. 3, then the rod is rotated and lifted asthe next cleaning ring is rotated between all helical springconvolutions to the other end or top, the rod rotation stopped, and therod lifted from the well.

While a square shape for the cleaning ring hole 28 and the correspondingbar head 30 is preferred, this shape may take the form of any otherdesired shaped polygon, if so desired.

METHOD FOR ASSEMBLING A SELF-CLEANING HELICAL SPRING FILTER

Another method disclosed herein is a new method for forming orassembling a self-cleaning helical spring filter which comprises thesteps of,

(1) inserting a ring shaped cleaner (25) between two convolutions at oneend of a helical tension spring (19),

(2) connecting each end of the helical tension spring of a predetermineddiameter and length to the opposite ends of an elongated perforatedouter sleeve (22) for spacing apart all spring convolutions by apredetermined distance, and

(3) forming a connecting means (square hole 27) on the ring shapedcleaner for being connected to a rotatable elongated bar (with a squareshaped head 30) for rotating the ring shaped cleaner between all of thespring convolutions to the spring other end for scraping off all foreignmaterial from between the spaced apart spring convolutions.

The first method step may be modified as follows,

(1) inserting a plurality of ring shaped cleaners (25, 26) betweenadjacent spring convolutions at the spring one end so that each may berotated, consecutively, between the adjacent spring convolutions to thespring other end for scraping off all foreign material from between thespaced apart convolutions for as many times as there are ring shapedcleaners.

The second step of the basic method above may be expanded to,

(1) fixedly connecting each end of the helical tension spring to one oftwo opposite short sleeves,

(2) fixedly connecting one short sleeve to an end of the elongatedperforated outer sleeve,

(3) twisting the other short sleeve to obtain the correct predeterminedspacing between all spring convolutions, and

(4) fixedly connecting the other short sleeve to the other end of theelongated perforated outer sleeve.

A further method step may be utilized by modifying the first basic stepthus,

(1) threading one or more cleaning rings on one end of the helicaltension spring prior to fixedly connecting each opposite end of thehelical tension spring to its respective short sleeve.

In more detail, the following method step may be utilized,

(1) forming the connecting means on the ring shaped cleaner to a polygonshaped opening therein for receiving a like and corresponding polygonshaped rotatable elongated bar for rotating the ring shaped cleanerbetween all of the spring convolutions to the spring other end forscraping off all foreign material from between the spaced apart springconvolutions.

Obviously other methods may be utilized for cleaning a helical springfilter with the embodiment of FIG. 2 than the one listed above,depending on the particular well conditions.

Accordingly, it will be seen that while a method for cleaning a helicalspring filter, a method for assembling a self-cleaning helical filter,and a self-cleaning helical spring filter are new and different, eachwill operate in a manner which meets each of the objects set forthhereinbefore.

While only two methods of the invention and one mechanism involved inthe methods have been disclosed, it will be evident that various othermethods and modifications are possible in the arrangement andconstruction of the disclosed methods and helical spring filter withoutdeparting from the scope of the invention and it is accordingly desiredto comprehend within the purview of this invention such modifications asmay be considered to fall within the scope of the appended claims.

I claim:
 1. A self-cleaning helical spring filter comprising,(a) helicalspring means connected at each end to an elongated perforated sleevemeans for spacing apart the spring convolutions by a predetermineddistance for forming a filter, (b) cleaning means positioned between twospring convolutions at one end of said spring, (c) axially movableelongated rotatable rod means having a bar portion and a head portionfor contacting said cleaning means, (d) means for attaching said rodmeans to means to rotate, and vertical displacement means, (e) saidcleaning means being engageable with said means to rotate by said headportion in response to said vertical displacement means, so as to rotatesaid cleaning means between all of the spring convolutions to saidspring means other end for scraping off all foreign material frombetween said spaced apart spring convolutions, and (f) said cleaningmeans being disengageable from said rod means by said bar portion inresponse to said vertical displacement means, so as to allow said rodmeans to pass axially through said cleaning means and to rotate thereinwithout rotating said cleaning means.
 2. A self-cleaning helical springfilter as recited in claim 1 wherein,(a) said elongated perforatedsleeve means has a short sleeve means attached in each end thereof, and(b) said helical spring means being connected in tension between saidtwo short sleeve means for spacing apart all spring convolutions by thepredetermined distance apart for forming the filter.
 3. A self-cleaninghelical spring filter as recited in claim 2 wherein,(a) each of said twoopposite ends of said helical spring means being welded to each of saidopposite short sleeve means, and (b) each of said two short sleeve meansbeing pinned to opposite ends of said elongated perforated sleeve meansfor spacing apart all spring convolutions by the predetermined distanceapart for forming the filter.
 4. A self-cleaning helical spring filteras recited in claim 1 wherein,(a) said cleaning means comprises a ringwith a polygon shaped opening in the center thereof, and (b) saidaxially movable elongated rotatable rod means having a similar polygonshaped end for fitting in said ring opening for rotating said ring forscraping off the foreign material from between said spaced apart springconvolutions.
 5. A self-cleaning helical spring filter as recited inclaim 1 wherein,(a) each of a plurality of cleaning means is positionedbetween two different spring convolutions at one end of said spring, and(b) said plurality of cleaning means being responsive to said axiallymovable rotating rod means head portion and bar portion for beingrotated, consecutively, to said spring means other end for scraping offall foreign material from between said spaced apart spring convolutionsfor as many times as there are cleaning means.